|Publication number||US4834106 A|
|Application number||US 07/151,154|
|Publication date||May 30, 1989|
|Filing date||Feb 1, 1988|
|Priority date||Feb 4, 1987|
|Also published as||EP0278304A1|
|Publication number||07151154, 151154, US 4834106 A, US 4834106A, US-A-4834106, US4834106 A, US4834106A|
|Inventors||Dietrich Hassler, Erhard Schmidt|
|Original Assignee||Siemens Aktiengesellschaft|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (5), Referenced by (7), Classifications (8), Legal Events (4)|
|External Links: USPTO, USPTO Assignment, Espacenet|
1. Field of the Invention
The present invention relates to lithotripsy devices, and in particular to such devices combined with a means for locating the calculus to be disintegrated in the body of a patient.
2. Description of the Prior Art
A shock wave device for disintegrating a calculus in the human body is generally described, for example, in German OS No. 33 28 039. A shock wave tube is used as the shock wave source. The shock wave tube has an electrical coil, an insulating foil, and a copper membrane arranged in sequence. When a current pulse is applied to the coil, eddy currents are generated in the membrane, causing the membrane to be rapidly repelled from the coil. A shock wave is formed in the adjacent transmission medium, such as water. The shock wave is focussed by an acoustic lens having a focal point disposed in the calculus of the patient after a suitable positioning procedure. The calculus may be, for example, a kidney stone.
Locating the position of the calculus in the body of the patient is of great significance to the degree of therapeutic success, as well as for decreasing the load on the patient during therapy. The chances for successful therapy increase, and the load on the patient decrease, as the targeting becomes more precise. It is known to undertake such locating using x-ray devices. A disadvantage of such conventional locating means, however, is that the position of the calculus cannot be monitored during the complete shock wave treatment, because this would result in an undesireable x-radiation load on the patient. X-ray images are therefore recorded only from time to time during therapy to monitor the position of the calculus.
For continuously monitoring the calculus position, it is known to use an ultrasound system as the locating means. For example, German Patent No. 34 27 001 corresponding to U.S. Pat. No. 4,669,483 discloses a locating and positioning method wherein the calculus is located with an ultrasound oscillator, prescribed identification marks are set, and the calculus and the focal point of the shock wave system are subsequently mechanically brought into coincidence.
It is also known from German OS No. 31 19 295 corresponding to U.S. Pat. No. 4,526,168 to undertake locating of the calculus using the shock wave sour In the system described therein, the shock wave source is an arrangement of a plurality of piezo-electric transducer elements. This method, however, can be used only given shock wave sources wherein the shock wave pulse is produced using such piezo-electric elements.
It is an object of the present invention to provide a lithotripter having an ultrasound locating means integrated therewith for continuously monitoring the position of the calculus, the ultrasound locating means being integrable with the lithotripter regardless of the type of shock wave source used.
It is another object of the present invention to provide such a lithotripter which permits the calculus position to be monitored during the action of the shock wave pulses thereon.
The above objects are achieved in accordance with the principles of the present invention in a lithotripter having a semi-transmissive acoustic mirror disposed between the shock wave source and the focussing means. An ultrasound transducer, which is part of an ultrasound sector scanner, is disposed in the lithotripter laterally of the acoustic mirror. The shock waves pass sufficiently unimpeded through the acoustic mirror so that calculus disintegration still is accomplished, but a sufficient portion of the ultrasound waves transmitted and received between the transducer and the calculus are reflected by the mirror to still permit locating and observation of the calculus.
The mirror is preferably planar. It is possible, however, to employ a mirror with a suitable curvature, which can be selected to achieve a particular scan format.
The shock wave pulse passing through the acoustic mirror is attenuated only slightly. Reflections arise at both boundary surfaces (front and back sides). The acoustic mirror is therefore relatively thin, because the superimposition of the two reflections generate two images shifted relative to each other in the propagation direction. This shift will be decreased as the mirror is made thinner. The loss of energy due to reflection and attenuation at the acoustic mirror for both the shock waves and the locating pulses can be compensated by using a slightly higher transmission energy.
The respective degrees of sound energy which are transmitted and reflected by the acoustic mirror can be set by selection of the characteristic acoustic impedence of the mirror. The attenuation of the shock wave pulse in the mirror can be compensated by using a pulse having a higher initial amplitude than would otherwise be used. The shock wave otherwise assumes an unimpeded course through the acoustic mirror. The ultrasound locating signal generated by the ultrasound transducer is laterally reflected by the acoustic mirror and directed toward the calculus. The ultrasound signals reflected by the calculus are in turn laterally reflected by the acoustic mirror toward the ultrasound transducer. The reflected echos are thus received by the transducer, and analyzed by the processing circuitry in the ultrasound sector scanner. Continuous observation of the position of the calculus is thus possible, even during the action of the shock wave pulse on the calculus.
The single FIGURE is a side sectional view of a lithotripter with an ultrasound locating means integrated therewith constructed in accordance with the principles of the present invention.
A lithotripter is shown in the drawing constructed in accordance with the principles of the present invention, and having a shock wave source generally referenced at 1. The shock wave source 1 includes a flat electrical coil 3 having a metallic membrane 7 (consisting of, for example, copper) disposed in front thereof, and separated from the coil 3 by an insulating foil 5. The coil 3 may be charged with a voltage pulse U. An approach path 9 follows the membrane 7. An acoustic lens 11, functioning as a focussing means for the shock wave pulses, is disposed in the approach path 9. The approach path 9 is terminated at the side closest to the patient by a coupling membrane 13. A housing is formed by a cylindrical tube 15, closed at one end by the shock wave source 1 and at the other end by the coupling membrane 13. The interior is filled with a coupling fluid, such as water.
The coupling membrane 13 is positioned against the skin of a patient 17. The shock wave source 1 is positioned so that the focus F of the acoustic lens 11 is coincident with the position of a calculus 19, for example, a kidney stone.
As seen in the shock wave propagation direction, a semitransmissive planar acoustic mirror 27 is disposed in front of the acoustic lens 11. The acoustic mirror 27 is preferably disposed at an angle α relative to the central axis 25 of the lens 11, the angle α preferably being 45°. The acoustic mirror 27 is rigidly placed preferably approximately half way between the shock wave source 1 and the acoustic lens 11.
An ultrasound transducer 21, which is part of a mechanical ultrasound sector scanner 22, is mounted to the interior of the tube 15 laterally opposite the acoustic mirror 27. The ultrasound transducer 21 is rotatable, as schematically indicated by the double curved arrow 12, around an axis which is perpendicular to the plane of the drawing and which proceeds through point A. The point A may lie roughly on the wall of the tube 15. Fan-shaped ultrasound locating signals 31 emanating from the ultrasound transducer 21 and emitted in succession are reflected in the direction toward the acoustic lens 11 by the acoustic mirror 27. The lens 11 re-shapes these signals into a converging sector scan. The image generating system of the scanner 22 is adapted to the converging sector scan and, in contrast to conventional sector scans, does not make use of a divergent scan.
The ultrasound transducer 21 and the acoustic mirror 27 are preferably rotatable in combination around the central axis 25, as schematically indicated by the circular arrow 10, so that an examination region shaped like a truncated cone can be observed in the patient 17.
The acoustic mirror 27 is as thin as possible so that multiple reflections from the mirror 27 are as small as possible. The thickness is preferably less than 0.5 mm. The acoustic mirror 27 may consist of plastic, such as plexiglass. The position of the acoustic mirror 27 between the shock wave source 1 and the acoustic lens 11 is preferably selected so that the apparent origin A' of the ultrasound locating signals 31 lies on the emission surface of the shock wave source 1, i.e., on the membrane 7.
The convergent sector scan of the patient 17 is achieved by a suitable selection of the distance of the acoustic mirror 27 between the membrane 7 of the shock wave source 1 and the acoustic lens 11.
At least one advantage of the lithotripter described above is that the calculus 19 can be observed during the entire treatment. This includes the time during which the shock wave pulse acts on the calculus 19. Moreover, the approach path of the shock wave pulse can also be observed in the entire volume of the lithotripter, and can be suitably selected.
A synchronization unit (not shown) may additionally be provided, which triggers a shock wave pulse when the echo of the ultrasound signal is received by the transducer 21. At such a point in time, the ultrasound system is "looking" precisely at the calculus 19.
Although modifications and changes may be suggested by those skilled in the art it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3716826 *||Feb 2, 1970||Feb 13, 1973||American Express Invest||Acoustic to optical image converter|
|US4526168 *||Apr 26, 1982||Jul 2, 1985||Siemens Aktiengesellschaft||Apparatus for destroying calculi in body cavities|
|US4620545 *||Oct 31, 1984||Nov 4, 1986||Trutek Research, Inc.||Non-invasive destruction of kidney stones|
|US4669483 *||Jul 19, 1985||Jun 2, 1987||Dornier System Gmbh||Lithotripsy system having locating and orienting apparatus|
|DE3328039A1 *||Aug 3, 1983||Feb 21, 1985||Siemens Ag||Crushing device for concrements in the body of a living being|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US4915114 *||Sep 29, 1988||Apr 10, 1990||Siemens Aktiengesellschaft||Shock wave source having central locating system & disposed in a cavity free of shock waves|
|US4947830 *||Jan 19, 1989||Aug 14, 1990||Siemens Aktiengesellschaft||Shock wave generator for extracorporeal lithotripsy|
|US4979500 *||Aug 3, 1989||Dec 25, 1990||Siemens Aktiengesellschaft||Extracorporeal lithotripsy apparatus with transversely adjustable focus region|
|US5009232 *||Aug 11, 1989||Apr 23, 1991||Siemens Aktiengesellschaft||Extracorporeal lithotripsy apparatus using high intensity shock waves for calculus disintegration and low intensity shock waves for imaging|
|US5048527 *||Nov 16, 1988||Sep 17, 1991||Kabushiki Kaisha Toshiba||Shock wave treatment apparatus|
|US5072722 *||Oct 17, 1990||Dec 17, 1991||Siemens Aktiengesellschaft||Device for the spatial ultrasonic location of calculi|
|US5191560 *||Oct 15, 1991||Mar 2, 1993||Dornier Medizintechnik Gmbh||Sound wave generator for therapeutic purposes|
|U.S. Classification||600/439, 601/4|
|International Classification||A61B17/22, A61B8/00|
|Cooperative Classification||A61B17/2258, A61B8/00|
|European Classification||A61B8/00, A61B17/225P2|
|Feb 1, 1988||AS||Assignment|
Owner name: SIEMENS AKTIENGESELLSCHAFT, BERLIN AND MUNICH, GER
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:HASSLER, DIETRICH;SCHMIDT, ERHARD;REEL/FRAME:004823/0620
Effective date: 19880115
Owner name: SIEMENS AKTIENGESELLSCHAFT, A CORP. OF GERMANY,GER
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HASSLER, DIETRICH;SCHMIDT, ERHARD;REEL/FRAME:004823/0620
Effective date: 19880115
|Dec 29, 1992||REMI||Maintenance fee reminder mailed|
|May 30, 1993||LAPS||Lapse for failure to pay maintenance fees|
|Aug 17, 1993||FP||Expired due to failure to pay maintenance fee|
Effective date: 19930530